An Off-Chip Adjustable Relaxation Voltage Controlled Oscillator Circuit

Abstract

An off-chip adjustable relaxation voltage-controlled oscillator circuit belongs to the technical field of power electronics. It includes a current generation unit, a peak absorption unit, an oscillation and compensation unit and an output buffer unit. The current generated by the current generation unit is used to charge and discharge the capacitance in the oscillation and compensation unit, and the current can be given by off-chip. Adjust the voltage to control; the oscillation and compensation unit is used to generate the oscillation signal according to the charge and discharge of the capacitor, and use the current generated by the current generation unit to control the frequency of the oscillation signal, and can improve the adjustability of the oscillation frequency of the oscillation signal through compensation; spike The absorption unit is used to eliminate the voltage spikes caused by parasitic capacitance when switching between charge and discharge states, and improve the noise suppression capability; the output buffer unit is mainly used for shaping the output oscillation signal, which can remove the burr of the output signal, so that the output oscillation signal more ideal.

Description

technical field [0001] The invention belongs to the technical field of power electronics, in particular to an oscillator circuit, in particular to a relaxation type oscillator circuit capable of realizing off-chip voltage control and adjustable frequency. Background technique [0002] In many power management chips, the oscillator is a very important module that can generate a fixed clock frequency for use by other modules in the power system. Oscillators are mainly divided into harmonic oscillators and relaxation oscillators. Relaxation oscillators are mainly used to generate non-sinusoidal output signals, such as square wave signals. For the relaxation voltage controlled oscillator, the voltage is used as the input, the clock signal is used as the output, and the oscillation frequency determines the operating frequency of the system. [0003] The commonly used relaxation-type voltage-controlled oscillator is mainly a ring oscillator composed of cascaded multi-stage single...

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Problems solved by technology

[0004] Aiming at the problems of insufficient noise suppression ability, difficult frequency adjustment, limited adjustment range of output frequency and complicated circuit in the above-mentioned relaxation type oscillator in the prior art, the present invention proposes a relaxation type voltage controlled oscillator, The structure is simple, the current generation unit is used to provide current, which is used to charge and discharge the third capacitor in the oscillation and compensation unit to generate an oscillation signal of a specific frequency, and the off-chip adjustable voltage Vctrl is used to control the current generated by the current generation unit to adjust The frequency of the oscillating signal makes the frequency adjustment easier to control; in addition, the spike absorption unit can effectively eliminate the voltage spike caused by the parasitic capacitance when the charging and discharging state is switched, and improve the noise suppression ability

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